This article develops an analysis of disability according to which disabling conditions are properties of organisms embedded in sets of environments. We begin by presenting the three mainstream accounts of disability-the medical, social, and interactionist models-and rehearsing some known limitations. We argue that, because of their primary focus on etiology, all three models share, more or less implicitly, a problematic assumption. This is the tenet that disabilities are individual properties. The second part of the essay presents an "ecological" interpretation of disability, inspired by classic and contemporary research on biological niches. Our proposal preserves many insights underlying extant approaches, while allowing a more accurate characterization of the nature and experience of disability. We conclude by drawing some general implications of our analysis.